Pt100 | GUILCOR SENSORS

Pt100
Temperature sensors

Pt100 temperature sensors provide high accuracy and excellent stability, making them the industry standard for industrial temperature measurement.

Maximum precision
+/- 0.1°K

Minimum temperature
-200°C

Maximum temperature
+850°C

Minimum dimensions
3x30x50

Response time
Medium

Self-heating
Weak

Price
Medium

Drift
Weak

What is a Pt100 sensor ?

The Pt100 is the global standard for platinum resistance temperature detectors (RTD).

Its nominal resistance is 100 Ω at 0 °C, and it varies in a perfectly stable and reproducible manner with temperature.

Robust, precise, and universal, it is the most widely used sensor in industry, research, and HVAC.

Operating principle

The Pt100 exploits the physical property of pure platinum (99.99%): its resistivity increases linearly with temperature.

This variation is described by the Callendar–Van Dusen formula:

R(T) = R0[(1+A⋅T+B⋅T²+C⋅(T-100)⋅T³]

with :

R0 = 100 Ω
A = 3.9083 × 10⁻³
B = -5.775 × 10⁻⁷
C = -4,183 x 10−12 (pour T < 0 °C)

The result is a very stable, practically linear signal that is easy to digitize and calibrate.

Technical specifications

Parameter	Typical Value
Nominal resistance at 0 °C	100 Ω
Temperature coefficient (α)	0,00385 °C⁻¹
Measurement range	−200 °C to +850 °C
Linearity	Excellent
Element material	Pure platinium
Typical measuring current	0,1 → 1 mA
Response time	< 0,5 s (gain Ø3 mm)
Long-term drift	< 0,05 °C/year

Wiring configuration

Type	Description	Precision
2-wire	Simple, low-cost scheme.	⚠️ Average
3-wire	Partial compensation of cable resistance.	✅ Good
4-wire	Complete suppression of line errors.	🏆 Excellent

Self-heating

With a current ≤ 1 mA, self-heating remains < 0.05 °C even in open air.

In stagnant or encapsulated environments, it is advisable to reduce the current to avoid any internal overheating.

Application areas

🚗 Automotive instrumentation and energy

💨 HVAC and air conditioning systems

🧪 Test and calibration benches

🌡️ Thermal monitoring of engines and pumps

🏭 Industrial processes and automation

Should I choose a Pt100 sensor ?

Strengths points

🌍 Standard international
→ The Pt100 is the most standardized RTD sensor in the world, compatible with the majority of existing instruments and controllers.
📊 Ideal balance of precision / robustness
→ It combines excellent accuracy with superior mechanical stability, making it reliable even in harsh industrial environments.
🧠 Easy to calibrate
→ Thanks to its well-known response, the Pt100 can be easily calibrated at fixed points (0 °C and 100 °C) without significant drift.

Weaknesses points

💰 Price higher than NTC thermistors
→ Despite its reliability, the Pt100 remains more expensive to manufacture and implement.
⚙️ Moderate response time
→ The stability of platinum is accompanied by a thermal inertia slightly higher than that of a copper or nickel sensor.
🔌 Sensitive to the quality of the assembly
→ A wiring error (especially in 2 wires) can introduce a significant drift if the cable length is not compensated.

Useful information

Here is some useful information regarding Pt100 sensors.

Table of ohmic values

°C	0	1	2	3	4	5	6	7	8	9
0	100.00	100.39	100.78	101.17	101.56	101.95	102.34	102.73	103.12	103.51
10	103.90	104.29	104.68	105.07	105.46	105.85	106.24	106.63	107.02	107.40
20	107.79	108.18	108.57	108.96	109.35	109.73	110.12	110.51	110.90	111.28
30	111.67	112.06	112.45	112.83	113.22	113.61	113.99	114.38	114.77	115.15
40	115.54	115.93	116.31	116.70	117.08	117.47	117.85	118.24	118.62	119.01
50	119.40	119.78	120.16	120.55	120.93	121.32	121.70	122.09	122.47	122.86
60	123.24	123.62	124.01	124.39	124.77	125.16	125.54	125.92	126.31	126.69
70	127.07	127.45	127.84	128.22	128.60	128.98	129.37	129.75	130.13	130.51
80	130.89	131.27	131.66	132.04	132.42	132.80	133.18	133.56	133.94	134.32
90	134.70	135.08	135.46	135.84	136.22	136.60	136.98	137.36	137.74	138.12
100	138.50	138.88	139.26	139.64	140.02	140.39	140.77	141.15	141.53	141.91
110	142.29	142.66	143.04	143.42	143.80	144.17	144.55	144.93	145.31	145.68
120	146.06	146.44	146.81	147.19	147.57	147.94	148.32	148.70	149.07	149.45
130	149.82	150.20	150.57	150.95	151.33	151.70	152.08	152.45	152.83	153.20
140	153.58	153.95	154.32	154.70	155.07	155.45	155.82	156.19	156.57	156.94
150	157.31	157.69	158.06	158.43	158.81	159.18	159.55	159.93	160.30	160.67
160	161.04	161.42	161.79	162.16	162.53	162.90	163.27	163.65	164.02	164.39
170	164.76	165.13	165.50	165.87	166.24	166.61	166.98	167.35	167.72	168.09
180	168.46	168.83	169.20	169.57	169.94	170.31	170.68	171.05	171.42	171.19
190	172.16	172.53	172.90	173.26	173.63	174.00	174.37	174.74	175.10	175.47
200	175.84	176.21	176.57	176.94	177.31	177.68	178.04	178.41	178.78	179.14
210	179.51	179.88	180.24	180.61	180.97	181.34	181.71	182.07	182.44	182.80
220	183.17	183.53	183.90	184.26	184.63	184.99	185.36	185.72	186.09	186.45
230	186.82	187.18	187.54	187.91	188.27	188.63	189.00	189.36	189.72	190.09
240	190.45	190.81	191.18	191.54	191.90	192.26	192.63	192.99	193.35	193.71
250	194.07	194.44	194.80	195.16	195.52	195.88	196.24	196.60	196.96	197.33
260	197.69	198.05	198.41	198.77	199.13	199.49	199.85	200.21	200.57	200.93
270	201.29	201.65	202.01	202.36	202.72	203.08	203.44	203.80	204.16	204.52
280	204.88	205.23	205.59	205.95	206.31	206.67	207.02	207.38	207.74	208.10
290	208.45	208.81	209.17	209.52	209.88	210.24	210.59	210.95	211.31	211.66
300	212.02	212.37	212.73	213.09	213.44	213.8	214.15	214.51	214.86	215.22
310	215.57	215.93	216.28	216.64	216.99	217.35	217.70	218.05	218.41	218.76
320	219.12	219.47	219.82	220.18	220.53	220.88	221.24	221.59	221.94	222.29
330	222.65	223.00	223.35	223.70	224.06	224.41	224.76	225.11	225.46	225.81
340	226.17	226.52	226.87	227.22	227.57	227.92	228.27	228.62	228.97	229.32
350	229.67	230.02	230.37	230.72	231.07	231.42	231.77	232.12	232.47	232.82
360	233.17	233.52	233.87	234.22	234.56	234.91	235.26	235.61	235.96	236.31
370	236.65	237.00	237.35	237.70	238.04	238.39	238.74	239.09	239.43	239.78
380	240.13	240.47	240.82	241.17	241.51	241.86	242.20	242.55	242.90	243.24
390	243.59	243.93	244.28	244.62	244.97	245.31	245.66	246.00	246.35	246.69
400	247.04

Precision class table

Temperature (°C)	Classe B	Classe A	Classe 1/3 B (DIN)	Classe 1/10 B (DIN)
-200	1.30	0.55	0.39	0.38
-150	1.05	0.45	0.23	0.21
-100	0.80	0.35	0.15	0.12
-90	0.75	0.33	0.14	0.10
-80	0.70	0.31	0.13	0.09
-70	0.65	0.29	0.12	0.08
-60	0.60	0.27	0.11	0.07
-50	0.55	0.25	0.10	0.06
-40	0.50	0.23	0.10	0.06
-30	0.45	0.21	0.09	0.05
-20	0.40	0.19	0.09	0.04
-10	0.37	0.17	0.08	0.03
0	0.30	0.15	0.08	0.03
10	0.35	0.17	0.09	0.04
20	0.40	0.19	0.10	0.04
30	0.45	0.21	0.11	0.05
40	0.50	0.23	0.12	0.06
50	0.55	0.25	0.13	0.07
60	0.60	0.27	0.14	0.08
70	0.65	0.29	0.16	0.09
80	0.70	0.31	0.17	0.10
90	0.75	0.33	0.18	0.11
100	0.80	0.35	0.19	0.12
110	0.85	0.37	0.20	0.13
120	0.90	0.39	0.21	0.14
130	0.95	0.41	0.22	0.15
140	1.00	0.43	0.24	0.15
150	1.05	0.45	0.25	0.16
160	1.10	0.47	0.26	0.17
170	1.15	0.49	0.27	0.18
180	1.20	0.51	0.29	0.19
190	1.25	0.53	0.30	0.21
200	1.30	0.55	0.31	0.22

Example of application of the linearization equation of a PT100

The Pt100 follows the famous Callendar–Van Dusen equation, used in almost all precision temperature measurement instruments:

For T ≥ 0 °C, the CCC component becomes negligible.

🔹 Example 1 : calculation of resistance at 100 °C

✅ Result : at 100 °C, the resistance of the Pt100 is approximately 138.5 Ω.

🔹 Example 2: calculating the temperature from a measured resistance

We measure R = 118.1 Ω. What is the temperature ?

✅ Result : the corresponding temperature is approximately 46 °C.

🔹 Practical remarks

The equation is integrated by default in most industrial temperature controllers and converters.
For microcontrollers, it can be implemented via a simple polynomial function or replaced by an R/T table.
The typical error between the equation and the standardized IEC 60751 tables is less than ±0.05 °C.

Integration diagram in an electronic system

Grâce à sa résistance nominale de 100 Ω, le Pt100 produit un signal exploitable sans amplification extrême, tout en gardant une très bonne immunité au bruit.

Il s’utilise avec une source de courant stable ou un pont de Wheatstone et un amplificateur différentiel.

🔹 Composants typiques

Component	Function
RTD Pt100 (3 or 4 wires)	Sensitive platinum element
Current source (0.3 mA)	Feed the probe without overheating
INA333 / AD8426 Amplifier	Amplify the weak signal
16 to 24 bit ADC	Analog-to-digital conversion
Microcontroller (STM32, ESP32, Arduino)	Calculation T = f(R) + compensation
RC filtering / shielding	Reduction of pests and noise

🔹 Functional diagram (ASCII)

             			+5 V
              │
     Current source (0.3 mA)
              │
           [ Pt100 ]
     (2 power wires + 2 measurement wires)
         │                  │
         │                  │
 Differential amplifier ──→ 24-bit ADC
                          │
                  [ Microcontroller ]
               (Calculating T = f(R) + display)